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Keywords = wet blue recycling

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17 pages, 2398 KiB  
Article
Mesoporous SBA-15-Supported Ceria–Cadmium Composites for Fast Degradation of Methylene Blue in Aqueous Systems
by Dănuţa Matei, Abubakar Usman Katsina, Diana-Luciana Cursaru and Sonia Mihai
Water 2025, 17(12), 1834; https://doi.org/10.3390/w17121834 - 19 Jun 2025
Viewed by 483
Abstract
A composite photocatalyst of ceria–cadmium supported on mesoporous SBA-15 silica was synthesized and employed for the aqueous methylene blue (MB) degradation. The composites were prepared using an incipient wetness impregnation technique and a conventional sol–gel approach with triblock copolymer P123 as a structure-directing [...] Read more.
A composite photocatalyst of ceria–cadmium supported on mesoporous SBA-15 silica was synthesized and employed for the aqueous methylene blue (MB) degradation. The composites were prepared using an incipient wetness impregnation technique and a conventional sol–gel approach with triblock copolymer P123 as a structure-directing agent for SBA-15 preparation, enabling the uniform dispersion of CeO2 and Cd species within the SBA-15 framework. The physicochemical properties of both CeO2/SBA-15 and Cd-CeO2/SBA-15 composites were analyzed using small-angle and wide-angle XRD, FT-IR spectroscopy, SEM, TEM, EDX spectroscopy, N2 physisorption at 77 K, and UV-Vis spectroscopy. The findings revealed that the SBA-15 support retained its well-ordered hexagonal mesostructure in both the ceria–SBA-15 and SBA-15-supported cadmium–ceria (Cd-CeO2) composites. The highest degradation efficiency of 96.40% was achieved under optimal conditions, and kinetic analysis using the Langmuir–Hinshelwood model indicated that the MB degradation process followed pseudo-first-order kinetics, with a strong correlation coefficient (R2 = 0.9925) and a rate constant (k) of 0.02532 min−1. Under irradiation, the Cd-CeO2/SBA-15 composites exhibited superior photocatalytic activity compared to the pristine components, owing to the synergistic interaction between ceria and cadmium, enhanced light absorption, and improved charge carrier separation. The recyclability test demonstrated that the degradation efficiency decreased slightly from 96.40% to 94.86% after three cycles, confirming the stability and reusability of Cd-CeO2/SBA-15 composites. The photocatalytic process demonstrated a favorable electrical energy per order (EE/O) value of 281.8 kWh m−3, indicating promising energy efficiency for practical wastewater treatment. These results highlight the excellent photocatalytic performance and durability of the synthesized Cd-CeO2/SBA-15 composites, making them promising candidates for facilitating the photocatalytic decomposition of MB and other dye molecules in water treatment applications. Full article
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22 pages, 3999 KiB  
Article
Leather Waste Hydrolysation, Carbonization, and Microbial Treatment for Nitrogen Recovery by Ryegrass Cultivation
by Ksawery Kuligowski, Dawid Skrzypczak, Katarzyna Mikula, Katarzyna Chojnacka, Paulina Bandrów, Robert Tylingo, Szymon Mania, Adrian Woźniak and Adam Cenian
Materials 2024, 17(23), 5741; https://doi.org/10.3390/ma17235741 - 23 Nov 2024
Cited by 1 | Viewed by 1314
Abstract
Leather waste contains up to 10% nitrogen (N); thus, combustion or gasification only for the energy recovery would not be rational, if safety standards are met. On the other hand, the chromium (Cr) content exceeding 5% in half of the waste stream ( [...] Read more.
Leather waste contains up to 10% nitrogen (N); thus, combustion or gasification only for the energy recovery would not be rational, if safety standards are met. On the other hand, the chromium (Cr) content exceeding 5% in half of the waste stream (w/w) is too significant to be applied in agriculture. In this work, four acid hydrolysates from leather waste shavings, both wet-white free of Cr and wet-blue with Cr, were used: two with a mixture of acids and supplemented with Cu, Mn, and Zn, and the other two as semi-products from collagen extraction using hydrochloric acid. Additionally wet-green leather waste shavings, e.g., impregnated with olive extract, were used followed by the two treatments: amendment with a biochar from “wet white” leather waste shavings and amendment with this biochar incubated with the commercial phosphorus stimulating microbial consortia BactoFos. They were applied as organic nitrogen-based fertilizers in a glasshouse experiment, consisting of 4–5 subsequent harvests every 30 days, under spring–autumn conditions in northern Poland. Biochar-amended wet-greens provided the highest nitrogen use efficiencies, exceeding 100% after 4 months of growth (for 20 kg N/ha) and varying from 17% to 37% in particular months. This is backed up by another parameter (relative agronomic effectiveness) that for these materials exceeded 150% for a single month and in total was around 33%. Biochar amendments significantly increased agronomic parameters for wet-greens, and their microbial treatment enhanced them even further. Recycling this type of waste can replace inorganic fertilizers, reducing greenhouse gas emissions and carbon footprint. Full article
(This article belongs to the Special Issue Current Approaches to Biomass Waste Material Utilization)
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13 pages, 2934 KiB  
Article
Recovery and Restructuring of Fine and Coarse Soil Fractions as Earthen Construction Materials
by Mazhar Hussain, Ines Lamrous, Antony Provost, Nathalie Leblanc, Hafida Zmamou, Daniel Levacher and Abdoulaye Kane
Sustainability 2024, 16(20), 8952; https://doi.org/10.3390/su16208952 - 16 Oct 2024
Viewed by 1278
Abstract
Excessive consumption of natural resources to meet the growing demands of building and infrastructure projects has put enormous stress on these resources. On the other hand, a significant quantity of soil is excavated for development activities across the globe and is usually treated [...] Read more.
Excessive consumption of natural resources to meet the growing demands of building and infrastructure projects has put enormous stress on these resources. On the other hand, a significant quantity of soil is excavated for development activities across the globe and is usually treated as waste material. This study explores the potential of excavated soils in the Brittany region of France for its reuse as earthen construction materials. Characterization of soil recovered from building sites was carried out to classify the soils and observe their suitability for earthen construction materials. These characteristics include mainly Atterberg limits, granulometry, organic matter and optimum moisture content. Soil samples were separated into fine and coarse particles through wet sieving. The percentage of fines (particles smaller than 0.063 mm) in studied soil samples range from 28% to 65%. The methylene blue value (MBV) for Lorient, Bruz and Polama soils is 1, 1.2 and 1.2 g/100 g, and French classification (Guide de terrassements des remblais et des couches de forme; GTR) of soil samples is A1, B5 and A1, respectively. The washing of soils with lower fine content helps to recover excellent-quality sand and gravel, which are a useful and precious resource. However, residual fine particles are a waste material. In this study, three soil formulations were used for manufacturing earth blocks. These formulations include raw soil, fines and restructured soil. In restructured soil, a fine fraction of soil smaller than 0.063 mm was mixed with 15% recycled sand. Restructuring of soil fine particles helps to improve soil matrix composition and suitability for earth bricks. Compressed-earth blocks of 4 × 4 × 16 cm were manufactured at a laboratory scale for flexural strength testing by using optimum molding moisture content and compaction through Proctor normal energy. Compressive strength tests were performed on cubic blocks of size 4 × 4 × 4 cm. Mechanical testing of bricks showed that bricks with raw soil had higher resistance with a maximum of 3.4 MPa for Lorient soil. Removal of coarse particles from soil decreased the strength of bricks considerably. Restructuring of fines with recycled sand improves their granular skeleton and increases the compressive strength and durability of bricks. Full article
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26 pages, 3154 KiB  
Review
Exploring Tannery Solid Wastes as a Source of Animal Feed
by Nelly Esther Flores Tapia and Hannibal Brito Moina
Processes 2023, 11(10), 2965; https://doi.org/10.3390/pr11102965 - 12 Oct 2023
Cited by 1 | Viewed by 3707
Abstract
This review delves into the processing of tannery solid waste, emphasizing fleshings and chromium-tanned leather waste. This paper centers on fat recovery, chromium elimination, and protein preservation, aiming to make them apt for animal consumption. This paper also assesses the potential of introducing [...] Read more.
This review delves into the processing of tannery solid waste, emphasizing fleshings and chromium-tanned leather waste. This paper centers on fat recovery, chromium elimination, and protein preservation, aiming to make them apt for animal consumption. This paper also assesses the potential of introducing such recycled products to the global market. Drawing on the literature from the past two decades, sourced comprehensively from Scopus and Web of Science, 36 articles were selected because of their significant contributions from leather production powerhouses such as India and Brazil. Fleshings have shown immense potential as animal feed, and the extraction of tallow and collagen from rawhide trimmings yields up to 98% and 93%, respectively. Fermented tannery fleshings, notably with Enterococcus faecium HAB01, also demonstrate strong antioxidant capabilities. The overarching consensus emphasizes the need for rigorous purification when dealing with chromium-containing wastes, addressing concerns tied to Cr (III) and Cr (VI). Furthermore, raw tannery fleshings stand out as a sustainable, cost-effective, and globally marketable solution for animal feed production. Full article
(This article belongs to the Special Issue Advances in Value-Added Products from Waste)
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17 pages, 4384 KiB  
Article
Cellulose Nanofibrils as a Damping Material for the Production of Highly Crystalline Nanosized Zeolite Y via Ball Milling
by Haya Nassrullah, Shaheen Fatima Anis, Boor Singh Lalia and Raed Hashaikeh
Materials 2022, 15(6), 2258; https://doi.org/10.3390/ma15062258 - 18 Mar 2022
Cited by 5 | Viewed by 2349
Abstract
Nanosized zeolite Y is used in various applications from catalysis in petroleum refining to nanofillers in water treatment membranes. Ball milling is a potential and fast technique to decrease the particle size of zeolite Y to the nano range. However, this technique is [...] Read more.
Nanosized zeolite Y is used in various applications from catalysis in petroleum refining to nanofillers in water treatment membranes. Ball milling is a potential and fast technique to decrease the particle size of zeolite Y to the nano range. However, this technique is associated with a significant loss of crystallinity. Therefore, in this study, we investigate the effect of adding biodegradable and recyclable cellulose nanofibrils (CNFs) to zeolite Y in a wet ball milling approach. CNFs are added to shield the zeolite Y particles from harsh milling conditions due to their high surface area, mechanical strength, and water gel-like format. Different zeolite Y to CNFs ratios were studied and compared to optimize the ball milling process. The results showed that the optimal zeolite Y to CNFs ratio is 1:1 to produce a median particle size diameter of 100 nm and crystallinity index of 32%. The size reduction process provided accessibility to the zeolite pores and as a result increased their adsorption capacity. The adsorption capacity of ball-milled particles for methylene blue increased to 29.26 mg/g compared to 10.66 mg/g of the pristine Zeolite. These results demonstrate the potential of using CNF in protecting zeolite Y particles and possibly other micro particles during ball milling. Full article
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13 pages, 4740 KiB  
Article
Constructing Er-Doped ZnO/CuS/Au Core-Shell Nanowires with Enhanced Photocatalytic and SERS Properties
by Chia-Man Chou, Tan-Tzu Chang, Chin-Yi Chen and Yu-Cheng Chang
Catalysts 2021, 11(11), 1347; https://doi.org/10.3390/catal11111347 - 9 Nov 2021
Cited by 12 | Viewed by 2909
Abstract
In this study, we fabricated Er-doped ZnO/CuS/Au core-shell nanowires using two-step wet chemical methods and an ion-sputtering method on a glass substrate as a bifunctional photocatalytic and surface-enhanced Raman scattering (SERS) substrate. The characteristic properties of as-prepared photocatalysts were confirmed by scanning electron [...] Read more.
In this study, we fabricated Er-doped ZnO/CuS/Au core-shell nanowires using two-step wet chemical methods and an ion-sputtering method on a glass substrate as a bifunctional photocatalytic and surface-enhanced Raman scattering (SERS) substrate. The characteristic properties of as-prepared photocatalysts were confirmed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, DR/UV-Vis spectroscopy, and photoluminescence spectroscopy. Compared with Er-doped ZnO nanowires and Er-doped ZnO/CuS core-shell nanowires, Er-doped ZnO/CuS/Au core-shell nanowires exhibited remarkably photocatalytic activity to degrade acid orange 7 solutions under blue LED light. These results ascribed to the Er-doped ZnO/CuS/Au core-shell nanowires can enhance the visible-light absorbance and the separation efficiency of photogenerated electron-hole pairs, inducing their higher photocatalytic activity under blue LED light. In addition, Er-doped ZnO/CuS/Au core-shell nanowires exhibit high sensitivity, a low detection limit (10−6 M), uniformity, recyclability, and stability of SERS performance for detected acid orange 7. Full article
(This article belongs to the Topic Nanomaterials for Sustainable Energy Applications)
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18 pages, 678 KiB  
Article
Preparation of Potassium Ferrate from Spent Steel Pickling Liquid
by Yu-Ling Wei, Yu-Shun Wang and Chia-Hung Liu
Metals 2015, 5(4), 1770-1787; https://doi.org/10.3390/met5041770 - 24 Sep 2015
Cited by 29 | Viewed by 9419
Abstract
Potassium ferrate (K2FeO4) is a multi-functional green reagent for water treatment with considerable combined effectiveness in oxidization, disinfection, coagulation, sterilization, adsorption, and deodorization, producing environment friendly Fe(III) end-products during the reactions. This study uses a simple method to lower [...] Read more.
Potassium ferrate (K2FeO4) is a multi-functional green reagent for water treatment with considerable combined effectiveness in oxidization, disinfection, coagulation, sterilization, adsorption, and deodorization, producing environment friendly Fe(III) end-products during the reactions. This study uses a simple method to lower Fe(VI) preparation cost by recycling iron from a spent steel pickling liquid as an iron source for preparing potassium ferrate with a wet oxidation method. The recycled iron is in powder form of ferrous (93%) and ferric chlorides (7%), as determined by X-ray Absorption Near Edge Spectrum (XANES) simulation. The synthesis method involves three steps, namely, oxidation of ferrous/ferric ions to form ferrate with NaOCl under alkaline conditions, substitution of sodium with potassium to form potassium ferrate, and continuously washing impurities with various organic solvents off the in-house ferrate. Characterization of the in-house product with various instruments, such as scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis), X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS), proves that product quality and purity are comparative to a commercialized one. Methylene blue (MB) de-colorization tests with in-house potassium ferrate shows that, within 30 min, almost all MB molecules are de-colorized at a Fe/carbon mole ratio of 2/1. Full article
(This article belongs to the Special Issue Hydrometallurgy)
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